Re: Disable scsi disk requests in QEMU when using virtio-blk device

[Arnabjyoti Kalita]

Hello Thomas,

Thank you very much for your input.

It seems scsi is "false" by default. I am not sure if "scsi=off" will
make any difference (is scsi=off the same as scsi=false?).

sudo ./qemu-system-x86_64 -device virtio-blk-pci,help

 ........
 rombar=<uint32>        -  (default: 1)
 romfile=<str>
 scsi=<bool>            - on/off (default: false)
 secs=<uint32>          -  (default: 0)
 .........

So, on another note, are these scsi interrupts/requests raised on
behalf of the virtio-blk device? I see virtio block specific
interrupts (vring_interrupt and virtblk_done) being raised by the
guest as well. Are these interrupts independent or related?

Best Regards,
Arnab


On Mon, Jul 19, 2021 at 11:55 AM Thomas Huth <thuth@redhat.com> wrote:
>
> On 18/07/2021 15.37, Arnabjyoti Kalita wrote:
> > Hello all,
> >
> > Is it possible to disable scsi disk requests being generated by the
> > guest when using a virtio-blk device?
> >
> > I am starting the guest in KVM mode using the below command line-
> >
> > sudo ./qemu-system-x86_64 -m 1024 --machine pc-i440fx-2.5 -cpu
> > qemu64,-kvmclock,-kvm_pv_eoi
> > -enable-kvm -netdev tap,id=tap1,ifname=tap0,script=no,downscript=no
> > -device virtio-net-pci,netdev=tap1,mac=00:00:00:00:00:00 -object
> > filter-replay,id=replay,netdev=tap1
> > -drive 
> > file=~/os_images_for_qemu/ubuntu-16.04-desktop-amd64.qcow2,format=qcow2,if=none,id=img-direct
> > -device virtio-blk-pci,drive=img-direct
>
> Try to replace the last line with:
>
>   -device virtio-blk-pci,drive=img-direct,scsi=off
>
> Generally, you can see a list of valid options for a device by running QEMU
> with something like:
>
>   qemu-system-x86_64 -device virtio-blk-pci,help
>
>   HTH,
>    Thomas
>